Decembep. 22, 1922] 



SCIENCE 



723 



the log p relation. The log p rela- 



T T 



tion gave straight lines in every case, and these 

 lines intersected sharply at the transition points. 

 Some transition points are definitely located by 

 the intersection of the vapor pressure curves. 

 There are certain limitations in using vapor pres- 

 sure data for interpreting the nature of the phe- 

 nomenon. 



Electroadsorption a« a pure chemical phenome- 

 non: J. "W. Elder, E. B. Starkey and N. E. 

 GoEDON. An investigaition to throw more light on 

 the relation between electroadsorption and pure 

 chemical action. The work was carried out with 

 the hydrogels of ferric oxide and silica acting as 

 the adsorbents. Such salts were used so as to 

 have the resulting products of different solubility 

 provided there was a chemical reaction. The elec- 

 troendosmosis of each system was investigated in 

 order to correlate, if possible, any electrochemical 

 behavior. 



Adsorpti07i by activated sugar charcoal. II: 

 F. E. Babtell and E. J. Millee. This paper 

 presents the results obtained in a study of the 

 nature of adsorption of electrolytes from solu- 

 tion by activaited ash-free sugar charcoal. It 

 includes data on the adsorption of acid dyes, 

 basic dyes, organic and inorganic acids and inor- 

 ganic bases. A brief discussion of the theory of 

 hydrolytio adsorption of oleeitrolytes is given, fol- 

 lowed by a consideration of results obtained witJi 

 a number of salt solutions with activated sugar 

 charcoal. The variation of these results from 

 those obtained by other investigators who have 

 used charcoals of animal or vegeitable origin is 

 X)ointed out. 



The influence of temperature pressure and cata 

 tyst support material upon adsorption by cata 

 lytic nicTcel : A. W. Gaugee and Hugh S. Tatloe, 

 (1) Adsorption isotherms of hydrogen on nicke 

 have been determined, using nitrogen as a refer 

 enoe gas. A definite saturation capacity of 

 nickel for hydrogen exists, dependent upon the 

 temperature; (2) From the variation of the sat- 

 uration pressure \vith temperature the heat of 

 adsorption of hydrogen on nickel has been calcu- 

 lated to be approximately 2,500 calories; (3) 

 The effect of using an inert material for catalyst 

 support has been found to increase greatly the 

 adsorptive capacity per gram of nickel and to 

 yield a catalyst that will stand much more severe 

 heat treatment without diminution of its adsorb- 

 ing power. 



An instrument for measuring the rate of swell- 



ing of gelatine films on rigid supports: S. E. 

 SiiEPPAKO and Felix A. Elliott. An instru- 

 ment was described which consists essentially of 

 a balance beam resting upon a fulcrum which 

 can be raised and lorivered by means of a 

 micrometer screw. At one end of the balance 

 beam hangs a slender but rigid quartz rod, the 

 end of iviiich is flattened to form a foot ca. 2 mm. 

 in diameter. The weight of this rod is carefully 

 counterbalanced ivithiu a few mgs., allowing just 

 enough "out of balance" to insure constant but 

 practically weightless contact between the foot 

 and the swelling gelatin surface. The gelatin 

 co<ated plate is securelj' clamped in a jacketed 

 tray just below the quartz rod. An optical 

 sytitem indicates the condition of balance, the ful- 

 crum is lowered umtil balance is indicated, a read- 

 ing made, and solution acting on the gelatin 

 poured in the tray and the fulcrum raised as may 

 be necessary to maintain balance. Readings are 

 made periodically. The sensitivity is about 0.001 

 mm. and the precision 5 to 1 per cent., depending 

 upon the rigidity of the jelly. Measurements 

 have been, made using glass (plates coated with 

 gelatin and also emulsion coated plates. These 

 were swollen in acids and alkalis as well as salt 

 solutions and photographic developing baths. 

 Although differing in degree all curves indicated 

 a rapid initial swelling asymptotically approach- 

 ing an equilibrium. 



Tlie effect of gravity and light on the forma- 

 tion .of Liesegang bands in gelatin and silicic 

 acid. (Illustrated) : Bael C. H. Davis. Gravitj' 

 has but little effect on the formation of periodic 

 bands in gelatin as shown experimentally. Light 

 is one of the most important variables in making 

 rhythmic bands of gold in silicic acid. At the con- 

 centrations used no bands were formed in the 

 dark at either 0° C. or at room temperatures. 

 Periodic variations of strong light and darkness 

 l^roduce bands in those regions in which there is 

 still adsorbed molecular gold, excess oxalic acid 

 and suitable amounts of the products of the 

 reaction. These by-products make precipitation 

 in bands possible because they influence the ten- 

 dency toward imbibition amd peptization so that 

 the gold is precipitated in "pockets" just large 

 enough to give a colloidal dispersion. There is 

 no fundamental difference between the bands of 

 blue gold and those of red. The location of the 

 colloidal bands can be governed by a bhick paper 

 which surrounds the tube and lias slits cut in it 

 at regular intervals. With a Mazda light placed 

 near such a tube in tlie dark room for a week 

 the bands at the openings are coarse particles 



